The present invention is directed to a system and method for automating the inspection of semiconductor wafers and other parts through the use of an acoustic micro imaging system or xe2x80x9cAMIxe2x80x9d system. An AMI system operated at the high resolutions needed to inspect semiconductor wafers and other parts having microscopic detail requires that the scanning ultrasonic (or xe2x80x9cacousticxe2x80x9d) beam be coupled to and from the inspected part through water, alcohol or other coupling fluid. The acoustic coupling between the acoustic beam generator, often called a xe2x80x9ctransducerxe2x80x9d, and the part is typically accomplished by submerging the beam generator and part in a bath or by creating a gravity or pressure jet or flow between the beam generator and the part through which the acoustic beam travels. The necessitated presence of this coupling fluid creates a very wet scanning environment.
It is common to store wafers in cassettes before and after they are inspected. However, it is important that the wafers after inspection in the wet-environment of the AMI be returned to their storage cassettes in a dry conditionxe2x80x94that is, not laden with significant surface moisture. Robots employed to handle wafers commonly employ a vacuum end effector. The wet-environment of an AMI system could be hostile to such commonly available wafer handling robots. Thus the presence of the coupling fluid creates a wet scanning environment that is inimical to automated AMI inspection processes.
Semiconductor wafers typically are circular in shape and are manufactured in a variety of diameters, including 100 mm, 125 mm, 150 mm, and recently 300 mm. During various manufacturing operations, semiconductor wafers are commonly retained by the use of a vacuum chuck having perforated vacuum plate upon which the wafers are situated. Such a vacuum chuck would be rendered inoperative in the wet AMI operating environment.
The processing of different size wafers requires different-sized vacuum chucks which presents yet another obstacle to a fully automated AMI inspection system.
It is an object of the present invention to provide an AMI system and method for automated inspection of semiconductor wafers and other parts which overcomes the innate incompatibility of commonly employed robotic devices and the hostile wet-environment of an AMI system, and satisfies the need to satisfactorily dry inspected parts before being returned to storage or passed on to another manufacturing process.
It is another object to provide an AMI system which makes possible the automated interchange of part-retention chucks capable of handling parts of different sizes and configurations.
It is a further object to provide for use in an AMI system a part-retention stage in which a vacuum chuck is so constructed as to be capable of quick-change, position-repeatable kinematic mounting without loss of vacuum integrity.
Many other objects will become evident from the following description and claims.